Abstract: In a pressure swing adsorption process, after the adsorption phase, the residual less adsorbable components are purged by the introduction of a gas consisting essentially of the more adsorbable component. The more adsorbable component is subsequently recovered by drawing a vacuum on the adsorber. When separating a gaseous mixture containing 40-75 mol % of the more adsorbable component, after a vacuum recovery step to 0.03-0.3 bar, a first pressure buildup phase is performed with a gas consisting essentially of less adsorbable components. Preferably, the gas is an unadsorbed gas exiting during the adsorption phase from another adsorber. The gas employed in the first pressure build up is introduced into the adsorber countercurrently to the adsorption direction until an intermediate pressure of 0.1-1 bar is reached. A further pressure buildup is then conducted, preferably with expansion gas from another adsorber and/or with the gaseous mixture to be separated.

Abstract: A pressure swing adsorption process is suggested conducted with three adsorbers. Cocurrent expansion gas obtained after termination of the adsorption phase is utilized initially for scavenging another adsorber. Additional cocurrent expansion gas serves for pressure buildup in the scavenged adsorber. Whereas this first pressure buildup is performed preferably in the adsorption direction, the subsequent pressurizing to adsorption pressure is conducted with the use of product gas in countercurrent mode. Furthermore, a special adsorber construction is proposed.